Email accounts of four senior aides at the National Republican Congressional Committee were compromised by cyberattackers. Attackers had complete credentialed access to the aides’ accounts and had been surveilling them for months. Thousands of email messages were exposed during this time. The incident was discovered in April, according to party officials. The NRCC asked security firm Crowdstrike to investigate; Crowdstrike had already been contracted to secure the committee’s internal networks, which reportedly were not compromised in this attack. For more, see here and here.”]
Source: https://www.darkreading.com/attacks-breaches/republican-committee-email-hacked-during-midterms